This was one of just three films released theatrically in "WarnerPhonic" sound, an early four-channel surround sound system. Unfortunately, only the mono version of the soundtrack has survived.
The general plot is based on a true story that Ernest Gann related in his 1961 autobiographical book about his flying career, "Fate is the Hunter". He and other pilots searched successfully for a lost fellow pilot in the wilds of northern Canada during World War II.
This is the first of two films in which Carl 'Alfalfa' Switzer appears as the copilot in a rescue plane searching for a character played by John Wayne. The first was the following year in Prigionieri del cielo (1954). As with the other film, he doesn't share any scenes with Wayne.
At one point the navigator is depicted as running and breathing hard. This is to be avoided in extreme cold, as the fast intake of breath prevents the air from absorbing any body heat wile simultaneously expelling all heated air from the lungs. The super-cooled air will then freeze the capillaries in the lungs and destroy them, with this being shortly replaced by scar tissue, If such vigorous exercise is continued over a period of time, the damage will be severe enough to fill the lungs with blood and cause death by suffocation.
The little yellow radio shown in the movie was a actual radio. Its design was based on a World War II German emergency transmitter. It is a BC-778/SCR-578/AN-CRT3 emergency transmitter (it could not receive) affectionately called "Gibson Girl", a name taken from the narrow-waisted female drawings of 1890s fashion artist Charles Gibson. Its shape allowed the operator to hold it between the legs while cranking it the necessary eighty RPM to produce enough electricity to operate. It could be set to automatically send an S.O.S. signal, or switched to send Morse Code signals. Early models transmitted only on 500kHz, later models also could transmit on 8,280kHz (later modified to 8,364kHz). It was notorious for being tough to crank.